Method for considering the subscriber type in mobility and radio resource management decisions in a radio access network

ABSTRACT

In order to efficiently allow mobility and radio resource management decisions on mobile networks the deciding entity (typically the radio access network) needs some understanding about the type of mobile user. In current cellular systems the radio network has only limited to null information about subscription dependent details of the mobile users. The proposed invention relates to a mobile system where a generic information container is defined which is applicable per UE in order to convey subscription related information from the core network to the radio access network which can be used to steer the user to an appropriate cell or for any other Radio Resource Management (RRM) related procedure/decision. It is proposed to define an information element (herein referred as “subscriber type”) which allows an indication or pointer to a set of rules which are locally defined in involved no&#39;des (e.g. CN SGSN, MSC, routers etc) and describe the “handling rules” to be applied in the RAN for each user of the mobile system independently.

BACKGROUND OF THE INVENTION

With the ongoing standardisation of 3GPP long term evolution (LTE orE-UTRAN) and WiMAX (IEEE802.16) air interfaces, in addition to existingstandards (GSM/GPRS and UMTS) an increasing diversity of radio accesstechnologies (RATs) will be present in future, Operators will requiresophisticated mobility mechanisms to simultaneously steer user toappropriates RATs while also spreading load across the differenttechnologies.

In today's wireless systems like GSM/GPRS or UMTS, typicallyUE-controlled cell reselection algorithms currently operateindependently of any subscriber-specific or service considerations [forUMTS e.g. in 3GPP TS 25.304]. All UEs are handled in the same way basedon parameter broadcast on the BCCH [for UMTS e.g. in 3GPP TS 25.331],and hence follow the same cell reselection strategies. Similar as forthe idle mode the decision criteria for both mobility related and radioresource related decisions are independent from any subscriber or usertype information. So in general the decisions is based on terminalcapabilities and to some extend on current service usage or specificinformation provided by the CN during the service establishment (e.g.so-called “service based handover” which gives an indication from the CNto the RAN that a certain bearer might be handed over to a specific RATor not). This all relates for the demand of providing similar serviceequally for all users of the mobile system.

With the advent of a demand for increased datarates and the costreduction implied by specific tariffs of the mobile operators anincreasing demand is foreseen for user as well as servicedifferentiation for example in mobility decisions. Qualifying data bymeans of Quality of Service (QoS) can provide some means todifferentiate the subscribers but mobility related decisions (especiallywhile being in idle mode) can't reliably be taken based on this kind ofinformation designed for differentiating traffic of different servicesusing prioritised packet delivery rather than independent tailored tocontrol mobility based upon the type of user.

3GPP have already specified access control classes to restrict access tomobile networks to a set of subscribers belonging to a set of accesscontrol classes during severe network congestion. It is proposed that asimilar kind of user differentiation is available within the RAN formobility decisions so that users can be spread appropriately acrossRATs.

In addition to load distribution across RATs, similar mechanisms mayalso be required to distribute load across different carriers ofdifferent bandwidths on the same RAT.

SUMMARY OF THE INVENTION

It is proposed to allow a procedure where an entity of the CN (e.g. aGWin case of SAE/LTE) informs the radio access network (e.g. the eNB incase of LTE/SAE) on registration of a UE or transition from LTE_IDLE toLTE_ACTIVE state about subscriber specific information which in turnshould be considered in the radio access network for mobility and radioresource management decisions, both in idle and active mode. Theinformation is preferably defined as an integer number which isassociated with the specific handling of the UE defined by a set ofrules. These rules will be defined locally in a eNB (or any otherinvolved node) by means of configuration files (e.g. using mainstreamdataformats like XML, etc) and will be applied by the eNB during themobility and radio resource management.

DETAILED DESCRIPTION OF THE INVENTION

The signalling from the CN (200) to the RAN (201) at registration of aUE or during the transition from LTE_IDLE to LTE_ACTIVE state (seeFIG. 1) will include a new “Subscriber Type” information element (in301) that can be used in mobility or other radio resource managementdecisions by the network (302). It could also be used to signal towardsthat UE that the UE has to follow only a specific part of the systeminformation broadcast (on the BCCH) in order to allow userdifferentiation also in terminal based decisions (e.g. for cellreselection purpose).

The coding of the information element should flexible enough to allowits application to a wide range of mobility applications. To allowsufficient granularity it is recommended that at least 16 classes aredefined,

One example of the use of the subscriber type field for load balancingbetween UMTS and LTE RATs is shown in FIG. 2. Assuming the LTE load isgreater that a certain threshold, it is desirable to spread users acrossthe different RATs based upon both the services used and the subscribertype.

Some services demanding especially-high data rates or minimum latencyare handled more appropriately on the more higher performing LTE RAT,independent of subscriber type. However, the majority of services arewell handled on both RATs, and the RAT selection for these ispredominantly based upon subscriber type. In this example, 8 classes ofsubscriber type are shown (number restricted for illustrative purposedonly), and for 3 subscriber types, most services are selected to behandled on the UMTS rather than the LTE RAT. Making subscriber type thedominant criterion rather than service reduces the amount of inter-RATmobility triggered by different service use, and also allows a moreconsistent RAT selection policy in IDLE and ACTIVE modes (FIG. 2).

The number of subscriber type classes selected for handling on the UMTSor LTE RATS can be made dependent on the load levels in both RATs. Inthe case of low LTE load, it is beneficial to handle all users on thebetter performing LTE RAT. At higher loads, it is possible to alter thenumber of subscriber type classes directed to the different RATsdepending upon the relative load on the two RATs. Another example of thesubscriber type information used in mobility decisions of a cellularnetwork is the case of network sharing or national roaming. In such acase typically on RAT (for example LTE) is shared among different mobileoperators while the technologies are not shared to the legacy reasons(e.g. UMTS or GSM). Typically the operator is interested getting the ownsubscriber back the the own network whenever possible. E.g. if thecoverage of the shared LTE network is left then the own subscribershould be preferably handed over to the right target network though bothmight fulfil the requirements for a HO target in terms of radioconditions. In such a case a “subscriber type” indication received formthe CN could be used to bring the correct subscriber in the correctnetwork. In today implementations this requirement can only be fulfilledby the analysis of an operator specific identity available in the RAN(namely the IMSI available in the RNC in UMTS, but not in the BSC of GSMnetworks). Having a RRM rule defined in the decisions nodes for alwaysperforming a handover of subscriber type X (from PLMN B) back to PLMN Bwhenever possible would be very flexible and could be enhanced/changeddepending on any subscription information available in the CN withoutrequiring any change to existing RAN implementations. Also securitywould benefit for the fact that no subscriber specific information isavailable in certain nodes of a network which might be vulnerable (e.g.the complete IMSI of a subscriber which can identify his identity).Having only an abstract “subscriber type” information and a defined“handling rule” available would ensure the subscribers confidentialityin all cases.

Another application for the usage of a “subscriber type” informationcould be related to the specific usage conditions of a terminal in acellular network. E.g. today in all cellular network that decisionfunctions in the network/RAN do not have any information how a specificterminal is used. E.g. it is not possible for the network with simplemeans to detect e.g. if a terminal is a stationary device such as a partof a machine or a wireless gateway router etc. The only means today toget this information is either to introduction of a specific signallingor the usage of radio measurements to determine if a terminal isstationary or not. Specifically the operation of the network withstationary wireless gateway routers (providing access of small home oroffice networks wireless to the internet) as well as stationarymachine-to-machine devices (gas/water counter) could benefit for theadditional information about the fact that the device is neither movingnor has strict power constrains as it is typically connected to a fixedpower supply: the network can take specific actions for such devices itwould not take for the majority of mobile devices in the cellularnetwork. One example could be to apply a specific timer for theLTE_ACTIVE to LTE_IDLE state transitions (which is either done to freeresources or to put the device in state where less power is consumed) orit could completely disable any measurements for mobility to be appliedby the device as it would never need to perform a handover to adifferent cell. The above listed examples are not exclusive, one canconsider even more scenarios where such information about the subscribertype could be beneficial.

1. A method which allows a radio access network (RAN) to selectivelyinfluence the mobility decisions as well as the radio resource controldecisions for a specific terminal based on information received from acore network (CN) entity.
 2. A method as in claim
 1. wherein the CNprovides an indication to the RAN on registration of an UE which issubscriber specific.
 3. A method as in claim
 1. wherein the CN providesan indication to the RAN on transition of a mobile from IDLE to ACTIVEmode which is subscriber specific.
 4. A method as in claim
 1. whereinthe information provided from the CN to the RAN is based on an index(“subscriber type”).
 5. A method as in claim
 1. wherein the CN choosesthe appropriate index (“subscriber type”) from information availablefrom the HLR.
 6. A method as in claim
 1. wherein the CN chooses theappropriate index (“subscriber type”) from information available fromthe any other instance of the CN.
 7. A method as in claim
 1. wherein theCN chooses the appropriate index (“subscriber type”) from informationnot related to subscription, but related to terminal capabilities.
 8. Amethod as in claim
 1. wherein the CN chooses the appropriate index(“subscriber type”) from information available from any other source. 9.A method as in claim
 1. wherein the CN chooses the appropriate index(“subscriber type”) from information depending on the users choice. 10.A method as in claim
 1. wherein the CN chooses the appropriate index(“subscriber type”) from information available from usage history of themobile subscriber.
 11. A method as in claim
 1. wherein the CN send theinformation to the RAN in the same message as the message which triggersthe transition of the mobile station from IDLE to ACTIVE.
 12. A methodas in claim
 1. wherein the configuration of the “handling rules” isdefined locally in each involved mode.
 13. A method as in claim 1.wherein the configuration of the “handling rules” is defined locally ineach involved mode by using an protocols which is used specifically forthis purpose.
 14. A method as in claim
 1. wherein the configuration ofthe “handling rules” is defined externally by a server and distributedto the involved nodes by means of “handling labels”
 15. A method as inclaim
 1. wherein the configuration of the “handling labels” is definedexternally by a server and distributed to the involved nodes by means ofe.g. XML or any other data format.
 16. A radio access network withdefined “handling rules” which acts during mobility and radio resourcemanagement decisions according to the indexed “handling rules” formobiles in ACTIVE mode.
 17. A radio access network with defined“handling rules” which acts during mobility and radio resourcemanagement decisions according to the indexed “handling rules” formobiles in IDLE mode. In order to do so, the RAN will identify and groupmobiles and assign “handling rules” to those mobile belonging to thesame group of subscriber (same index).
 18. A radio access network withdefined “handling rules” which provide different “mobility rules” byallocation different cell reselection parameter sets to different groupsof UEs depending on the subscriber information/index available per UE.19. A radio access network with defined “handling rules” which actsduring mobility and radio resource management decisions and signals toselective terminals an information which allows this terminal toselectively read the system information on the BCCH.
 20. A procedurewhere the information of which part of the system information of theBCCH is relevant is used by the terminal to apply differentiatedmobility decisions/procedures as if another part of the information fromthe BCCH would have been read.
 21. A method as in claim
 1. where thehandling rules depend on subscription information requested from theHLR, as well as service, load and other radio related information.
 22. Amethod as in claim
 1. where the handling rules depend on subscriptioninformation requested from the PCRF , as well as service, load and otherradio related information.
 23. A method as in claim
 1. where thehandling rules depend on the preference of a user, as well as service,load and other radio related information.
 24. A method as in claim 1.where the handling rules depend on the history of the users activity(e.g. if only voice calls were placed/received during the last Xhours/days), as well as service, load and other radio relatedinformation.
 25. A method as in claim
 1. where the handling rules dependon the type of terminal the user uses (e.g. mobile, laptop, home accesspoint (LAN router), vending machine, machine to machine device, . . . ),as well as service, load and other radio related information.